LG LM-W550A User manual

3CD CHANGER DVD
SERVICE MANUAL
MODEL: LM-W550A LM-U550D LMS-W550
SERVICE MANUAL MODEL: LM-W550A LM-W550A, LM-U550D LMS-W550

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[CONTENTS]
❍SECTION 1. GENERAL
• SERVICING PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5
❍SECTION 2. ELECTRICAL SECTION
• TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
• AUDIO PART TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21
• SCHEMATIC DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23
• WIREING DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-35
• PRINTED CIRCUIT DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-37
❍SECTION 3. EXPLODED VIEWS
• CABINET AND MAIN FRAME SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
• TAPE DECK MECHANISM (A/R & A/S : RIGHT A/R DECK) . . . . . . . . . . . . . . . . . . . . . . . . .3-3
• TAPE DECK MECHANISM (A/R & A/S : LEFT A/S DECK) . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5
• CD MECHANISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-7
❍SECTION 4. SPEAKER PART
• SPEAKER PART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
❍SECTION 5. REPLACEMENT PARTS LIST
• REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1

- 1-2 -
❏SERVICING PRECAUTIONS
• NOTES REGARDING HANDLING OF THE PICK-UP
1. Notes for transport and storage
1) The pick-up should always be left in its conductive bag until immediately prior to use.
2) The pick-up should never be subjected to external pressure or impact.
2. Repair notes
1) The pick-up incorporates a strong magnet, and so should never be brought close to magnetic materials.
2) The pick-up should always be handled correctly and carefully, taking care to avoid external pressure and
impact. If it is subjected to strong pressure or impact, the result may be an operational malfunction and/or
damage to the printed-circuit board.
3) Each and every pick-up is already individually adjusted to a high degree of precision, and for that reason
the adjustment point and installation screws should absolutely never be touched.
4) Laser beams may damage the eyes!
Absolutely never permit laser beams to enter the eyes!
Also NEVER switch ON the power to the laser output part (lens, etc.) of the pick-up if it is damaged.
5) Cleaning the lens surface
If there is dust on the lens surface, the dust should be cleaned away by using an air bush (such as used
for camera lens). The lens is held by a delicate spring. When cleaning the lens surface, therefore, a cotton
swab should be used, taking care not to distort this.
6) Never attempt to disassemble the pick-up.
Spring by excess pressure. If the lens is extremely dirty, apply isopropyl alcohol to the cotton swab. (Do
not use any other liquid cleaners, because they will damage the lens.) Take care not to use too much of
this alcohol on the swab, and do not allow the alcohol to get inside the pick-up.
Storage in conductive bag Drop impact
NEVER look directly at the laser beam, and don’t let
contact fingers or other exposed skin.
Magnet
How to hold the pick-up
Conductive Sheet
Cotton swab
Pressure
Pressure
SECTION 1. GENERAL

- 1-3 -
• NOTES REGARDING COMPACT DISC PLAYER REPAIRS
1. Preparations
1) Compact disc players incorporate a great many ICs as well as the pick-up (laser diode). These components
are sensitive to, and easily affected by, static electricity. If such static electricity is high voltage, components
can be damaged, and for that reason components should be handled with care.
2) The pick-up is composed of many optical components and other high-precision components. Care must be
taken, therefore, to avoid repair or storage where the temperature of humidity is high, where strong magnet-
ism is present, or where there is excessive dust.
2. Notes for repair
1) Before replacing a component part, first disconnect the power supply lead wire from the unit
2) All equipment, measuring instruments and tools must be grounded.
3) The workbench should be covered with a conductive sheet and grounded.
When removing the laser pick-up from its conductive bag, do not place the pick-up on the bag. (This is
because there is the possibility of damage by static electricity.)
4) To prevent AC leakage, the metal part of the soldering iron should be grounded.
5) Workers should be grounded by an armband (1M Ω)
6) Care should be taken not to permit the laser pick-up to come in contact with clothing, in order to prevent sta-
tic electricity changes in the clothing to escape from the armband.
7) The laser beam from the pick-up should NEVER be directly facing the eyes or bare skin.
CLEARING MALFUNCTION
You can reset your unit to initial status if malfunction occur(button malfunction, display, etc.).
Using a pointed good conductor(such as driver), simply short the RESET jump wire on the inside of
the volume knob for more than 3 seconds.
If you reset your unit, you must reenter all its settings(stations, clock, timer)
NOTE: 1. To operate the RESET jump wire, pull the volume rotary knob and release it.
2. If you wish to operate the RESET jump wire, it is necessary to unplug the power cord.
Resistor
(1 Mohm) Conductive
Sheet
Resistor
(1 Mohm)
Armband
RESET jump wire
VOLUME
VOLUME KNOB
DOWN
UP

- 1-4 -
❏ESD PRECAUTIONS
• Electrostatically Sensitive Devices (ESD)
Some semiconductor (solid state) devices can be damaged easily by static electricity. Such components
commonly are called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated
circuits and some field-effect transistors and semiconductor chip components. The following techniques should
be used to help reduce the incidence of component damage caused by static electricity.
1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off
any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a
commercially available discharging wrist strap device, which should be removed for potential shock reasons
prior to applying power to the unit under test.
2. After removing an electrical assembly equipped with ESD devices, place the assembly on a conductive sur-
face such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ESD devices.
4. Use only an anti-static solder removal device. Some solder removal devices not classified as "anti-static" can
generate electrical charges sufficient to damage ESD devices.
5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ESD
devices.
6. Do not remove a replacement ESD device from its protective package until immediately before you are
ready to install it. (Most replacement ESD devices are packaged with leads electrically shorted together by
conductive foam, aluminum foil or comparable conductive materials).
7. Immediately before removing the protective material from the leads of a replacement ESD device, touch the
protective material to the chassis or circuit assembly into which the device will by installed.
CAUTION : BE SURE NO POWER IS APPLIED TO THE CHASSIS OR CIRCUIT, AND OBSERVE ALL
OTHER SAFETY PRECAUTIONS.
8. Minimize bodily motions when handing unpackaged replacement ESD devices. (Otherwise harmless motion
such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can gen-
erate static electricity sufficient to damage an ESD device).
• CAUTION. GRAPHIC SYMBOLS
THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS INTENDED TO
ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED “DANGEROUS VOLTAGE” THAT
MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF ELECTRIC SHOCK.
THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE SERVICE PER-
SONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICE LITERATURE.

- 1-5 -
❏SPECIFICATIONS
NOTE : Specification are subject to change without notice in the course of product improvement.

- 1-6 -

- 2-1 -
VKK CHECK
P-SENS PART CHECK
CN701 3PIN DC -33V check
IC301 51PIN voltage check
SMPS Assy CN942 ➝ 5PIN 5V operation check
MAIN PCB CN701 5PIN 5V
MAIN PCB CN301 4PN 5V check
Refer to SMPS Troubleshooting
Refer to SMPS Troubleshooting
CN701 contact condition check
MAIN PCB PATTERN disconnection check
❏ TROUBLESHOOTING GUIDE
YES
YES
NO
NO
FRONT PN301 4PIN 5V check
FRONT IC304 operation status checck
u-COM 26PIN 5V check
YES
YES
YES
YES
YES
YES
NO
NO
Input voltage 4V or higer, output voltage
2.1V or higer operation check
IC304 KIA7042 replacement
SECTION 2. ELECTRICAL

- 2-2 -
Muting circuit Troublrshooting (MUTE condition)
Q752(A102) Base “HIGH”
Q604, Q605(D1302) BASE “HIGH” check
c-COM operation status check
Replace each related TR
Q603(A102) operation status check
Replace when Q603(A102) is defective
c-COM 2PIN(A-MUTE) LINE check
CN942/CN701 connection status
check
MUTE
YES
YES
YES
YES
NO
NO
NO
Unfelt voice
Input check (AUX ➝ 9.36 TUNER ➝ 6/39 TAPE ➝ 7/38CD ➝ 8/37PIN)
Check input and operation status for each function
YES NO
IC601 20/25PIN output check
Refer to IC401(NJW1190) IC specification
YES NO
IC601 input check (22/23PIN)
c-COM check and (CLK/DATA check)
YES NO
IC601 output check (24PIN)
NORMAL
Check IC401 24PIN cover 8V and power circuit
YES NO
Power operation staus check (DC12V)
R634 180(9.1)V check
YES
YES
NO

- 2-3 -
Specific FUNCTION MODE unfelt voice
TAPE
IC202 9PIN (PB MUTE) operation check
c-COM 301 3.4PIN CLK/DATA operation check
DECK HEAD WIRE connection status check
Refer to IC201 Troubleshooting
IC201 input check (HAED input) “A” DECK 32,39 “B” DECK 34,37
YES
YES
NO
IC202 14PIN HIGH operation check
Q212(A102) BASE LOW check
Q201.202(GATE) HIGH operation check
NO
IC201 output check (5, 26PIN)
IC401 7, 38 signal input check
YES
NO
Replace IC202
YES
NO
Q212(A101) EMITTER 5V check
Q213(C103 COLLECTOP LOW) operation check
Replace Q213(C103)
YES
NO
YES
Q201,202 (DRAIN) GND check
YES
Replace defective parts
YES
Q212(A102) COLLECTOR 5V operation check
YES
Replace defective parts
YES
NO
A
A

- 2-4 -
AUX
JK601 signal input check
IC401 9,36PIN signal input check
YES
YES
MIC
IC401 1PIN input check
Refer to IC404 Toubleshooting
YES
YES
TUNER
Refer to TUNERMODULE
IC401 6,39PIN signal input check
YES
YES
CD
Check CN601 1,3PIN signal anad Refer to CD Troubleshooting
IC601 8,37PIN signal input check
YES
YES
MAIN PCB PATTERN check
NO
B

- 2-5 -
IC301 Troubleshooting
MIC PCB
IC406 6PIN power check and 2PIN input check
YES
MIC input pattern disconnection check and
after MIC insertion
NO
IC406 7PIN output check
YES
MIC MUTE operation status check
NO
PN401 3PIN output check
YES
NORMAL
YES
IC406 7PIN output check
NO
Replace IC406
NO
Check PN401 connection status
and IC301 20PIN status check
NO
JK401 input check
Q302 collector HIGH operation
check
Q302 (Replace C102)
IC301 17,46,72,90 power impression check
SMPS power 5V check
YES NO
PN301 20PIN 5V impression chck
PN301 4PIN 5V P-SENS terminal check
YES NO
X301 ossillates or not?
Replace X301
YES NO
When IC301 11PIN power insert High ➝ LOW ➝ High
Replace IC301
Reset circuit check
YES NO
Q302(C102M) operation staus check
NORMAL
YES
YES
NO
B

- 2-6 -
IC401 (NJW1190) Troubleshooting
IC401 24PIN power impression check
Refer to SMPS power check
YES NO
IC401 22,23 Pulse waveform check (VOL UP,DOWN check while rotating VOL UP, DOWN
IC401 20,25 PIN waveform output check
IC301 10,8PIN check
IC401 7,37PIN(TAPE) input waveform check
YES
YES
YES
YES
NO
Replace IC601
NO
IC401 6,39(TUNER) PIN input waveform check
TAPE Troubleshooting
NO
IC401 8,37(CD) PIN input waveform check
TUNER module replacement
NO
YES NO
IC401 9, 36(AUXO input waveform check
CD Troubleshooting
Nomal
Replace IC401
NO
MICOM(10,8) - IC601(21,22) PATTERN check
YES
IC301 Troubleshooting
NO
IC302, 202 (BU2090) Troubleshooting
IC301, 201 16PIN power impression check
SMPS power check
YES NO
IC302,202 95,2,3PIN CLK data check
CONTROL function check
IC301 95,34,4PIN data check(When switching CD, TAPE FUNCTION)
NORMAL
YES
YES
NO
Replace IC302, 202 IC301, IC501 PATTERN check
NO
Pattern check between IC301 and IC501
YES
Refer to IC301 Troubleshooting
NO

- 2-7 -
AMP MODULE Troubleshooting
PN301, PN702 assembly status check
1. PN301(7,8), PN702(13,14) PWM DATA.CLK operation status check, PN301
PWM/CS534012PIN STA518A PWDN25 check
2. PN702:13PWM_SDA, 14PWM_SCL check
YES NO
YES NO
PN 7PIN 3.3V check power check
12.288MHz oscillation check
27PIN 3.3V check
YES
YES
YES
YES
YES
YES
SMPS power check
CS5340 2PIN MCLK/PS9813 48CLK_IN
Replace when 12.288 is defective
NO
IC702 41, 42, 43, 44 operation status check
SMPS power check
NO
IC801 power cehck
IC801 25,28PIN RESET check
NORMAL
OK
SMPS 32V power check
NO
IC301 79,81 PN301 12,14PIn check
NO
Play check
IC201 16PIN VCC power impression
IC201 5, 26PIN Signal Output check
IC201 14PIN Muting circuit check
Refer to SMPS power cehck
Replace IC201
Replace Deck Mecha
Deck Mecha operation performance check
YES
YES
YES
NO
NO
NO

- 2-8 -
Rec check (Q252, Q202 ON :R273, R223 High)
IC401 11,34 OUT check
IC401 each input 6, 39. TAPE. 7, 38. CD 8,38 AUX
9.36PIN signal input check
IC201 7,24PIN input check
IC201 10,21PIN output check
REC input check
Input LINE check
YES
YES
YES
NO
NO
L203 2,3PIN oscillation check
After REC output check, Replace defective IC
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
IC202 14PIN operation status check
IC202 4PIN operation check
Q205 Base 0.6V impression check
YES
Q213, 212 operation status check
YES
DECK replacement
YES
NO
Refer to power check
Q204 Collector Low
IC202 Troubleshooting check
Q203 replacement
Q204 replacement
NORMAL
L203 replacement

- 2-9 -
Dubbing check (“NORMAL or REC”//“HIGH”)
IC401 11,34 OUT check
IC401 each input TUNER 6, 39 TAPE 7, 38 CD 8, 38 AUX
9, 36 PIN signal input check
IC201 7, 24PIN input check
IC201 10,21PIN output check
REC input check
Input LINE check
YES
YES
YES

- 2-10 -
❏INTERNAL BLOCK DIAGRAM of ICs
• CS5340
BLOCK DIAGRAM
• NJW1190
BLOCK DIAGRAM

- 2-11 -
PIN FUNCTION (QFP48-P1)

- 2-12 -
• PS9813
BLOCK DIAGRAM
• Pin Assignment
PWM_CH2_M
CVDD2
DVSS3
PWM_LOL_MMSDIN
MBCK
PLL_AVSS
PLL_AVDD
MLRCK
NRESET
MIC_BCK
SLRCK
SSDIN
SBCK
EPD_ENA
MIC_LRCK
21
22
23
19
20
16
17
18
14
15
8
9
10
11
12
13
6
7
4
5
46
30
31
32
33
34
35
36
37
28
29
3
38
39
40
41
42
43
44
45
PWM_HP_L
PWM_LOR_M
DVDD2
DVDD1
PWM_CH1_M
DVSS2
PWM_CH2_P
PWM_CH3_P
PWM_CH3_M
PWM_LOR_P
PWM_LOL_P
OVERLOAD
PLL_DVDD
TEST_MODE2
TEST_MODE1
SCL
SA
CLK_IN
DVSS1
MCLK
SDA
27
26
48
47
2
1
MIC_SDIN 24
PWM_CH1_P
25
PS9813
PLL_DVSS
PLL_EXT_LPF
CVDD1
VSS
PWM_HP_R
PLL_AGS
N.C.
DVDD3
VSS

- 2-13 -
Pin Descriptions